The present invention relates to the field of mining machines, and particularly to a roll sizer for breaking apart and crushing mined material.
Conventional mining roll sizers include a pair of parallel counter-rotating roll assemblies positioned within a crushing chamber. The shafts are rotatably supported by bearings and include a series of picks arranged along the surface. The bearings on either end of the shaft are typically spherical bearings. As the roll assemblies rotate, the picks engage material that is fed into the crushing chamber, exerting a compressive force on the material and breaking the material apart until it is small enough to pass around the rolls. During normal operation, the material exerts a reaction force on the shafts in a direction that is oblique to a shaft axis. This is especially true if a piece of hard material, or tramp material is fed into the crushing chamber. These reaction forces increase a localized radial load on the bearings and increase bearing misalignment. This causes the bearings to wear at a faster rate, ultimately requiring more maintenance and more down time of the roll sizer.